AA default value?

[Janice Caron]

The big problem for me with associative arrays is that I often have to
write ugly code like:

    auto p = key in aa;
    if (p)
    {
    	auto val = *p;
    }
    else
    {
        /* whatever */
    }

instead of merely

    auto val = aa[key];

In order to avoid superfluous lookups, the code that I actually end up
writing doesn't use the square brackets at all, which kind of defeats
the object of the built-in array-like syntax. What would seriously
make for nicely readable code would be if the behavior of aa[key]
could be changed. Currently, aa[key] throws an exception (in Debug
mode) or falls over (in Release mode) if key does not exist. Wouldn't
it be nicer if, instead, it simply returned

	typeof(aa[key]).init

if the key was not present in the array? Or perhaps an even more
exotic syntax like

    auto val = aa[key; defaultValue];

might work.

(None of this would preclude people from using "in" if they explicitly
wanted to check).